Carrier head for chemical mechanical polishing system

ABSTRACT

Disclosed herein is a carrier head for a chemical mechanical polishing system. The carrier head for a chemical mechanical polishing system includes a base. A substrate receiving member having an outer surface against which a substrate can be mounted is connected to a lower part of the base. Inside of the substrate receiving member, at least two bladders are connected to the lower part of the base. The at least two bladders can apply pressure independently to predetermined areas of an inner surface of the substrate receiving member by expanding and contacting the inner surface. At least one wall structure is connected to the lower part of the base, wherein the at least one wall structure can limit lateral expansions of the at least two bladders.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a chemical mechanical polishing system,and more particularly, to a carrier head for applying polishing pressureto a substrate during chemical mechanical polishing process.

2. Description of the Related Art

When manufacturing semiconductor or glass substrates, and fabricatingintegrated circuits, a need to polish or planarize the surface of asubstrate at particular steps has been increased. As a technology tosatisfy the need, a chemical mechanical polishing (CMP) has been widelyused.

In general, the CMP of a substrate is performed by attaching a polishingpad on a platen, mounting the substrate to a substrate receiving unitcalled a carrier head, and then, while applying slurry to the polishingpad, rotating the platen and carrier head simultaneously to generatefriction between the polishing pad and the substrate.

Basically, the carrier head comprises a base which receives motive powerfrom a drive shaft and provides space in which carrier parts are capableof being installed, a substrate receiving member to which a substrate ismounted, and a retaining ring which supports a side surface of thesubstrate during the polishing process to prevent the substrate fromslipping out from the beneath of the carrier head. During CMP, thesubstrate is applied with polishing pressure through the substratereceiving member. However, even though the polishing pressure is applieduniformly on the entire substrate, a specific area of the substrate (forexample, an edge area of the substrate) may have a different polishingrate from those of other area according to the nature of polished layer,polishing pad, or slurry. In this case, in order to maintain goodpolishing rate uniformity, there is a need to adjust the polishing rateat specific areas by independently controlling the polishing pressureapplied to each predetermined area of the substrate.

SUMMARY OF THE INVENTION

The present invention has been made in an effort to provide a carrierhead for a chemical mechanical polishing system capable of independentlyapplying polishing pressure to each predetermined area of a substrateduring a chemical mechanical polishing.

In one aspect, the invention is directed to a carrier head for use in achemical mechanical polishing system. The carrier head comprises: abase; a substrate receiving member connected to a lower part of thebase, having an outer surface against which a substrate can be mounted;at least two bladders positioned inside of the substrate receivingmember and connected to the lower part of the base, wherein the at leasttwo bladders can apply pressure independently to predetermined areas ofan inner surface of the substrate receiving member by expanding andcontacting the inner surface; and at least one wall structure connectedto the lower part of the base, wherein the at least one wall structurecan limit lateral expansions of the at least two bladders.

In another aspect, the carrier head comprises: a base; a substratereceiving member connected to a lower part of the base, having an outersurface against which a substrate can be mounted; a bladder positionedinside of the substrate receiving member and connected to the lower partof the base, wherein the bladder can apply pressure to a predeterminedarea of an inner surface of the substrate receiving member by expandingand contacting the inner surface; and at least one wall structureconnected to the lower part of the base, wherein the at least one wallstructure can limit a lateral expansion of the bladder.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view of a carrier head accordingto a preferred embodiment of the present invention.

FIG. 2 is a perspective view illustrating an exemplary embodiment of acenter bladder.

FIG. 3 is a perspective view illustrating an exemplary embodiment of anedge bladder.

FIG. 4 is a top view illustrating an exemplary embodiment of a bladderclamp for securing a center bladder.

FIG. 5 is a top view illustrating an exemplary embodiment of a bladderclamp for securing an edge bladder.

FIG. 6 is a perspective view illustrating an exemplary embodiment of awall structure.

FIG. 7 is a perspective view illustrating another exemplary embodimentof a wall structure.

FIG. 8 is a schematic cross-sectional view of a carrier head thatincludes an edge bladder which is clamped externally according toanother exemplary embodiment.

FIG. 9 is a perspective view illustrating an exemplary embodiment of theedge bladder shown in FIG. 8.

FIG. 10 is a cross-sectional view along line AA′ of FIG. 9.

FIG. 11 is a cross-sectional view illustrating an exemplary embodimentof an edge bladder that includes a round bottom portion.

FIG. 12 is a cross-sectional view illustrating an exemplary embodimentof an edge bladder that includes pleats at side portions.

FIGS. 13 and 14 are cross-sectional views illustrating exemplaryembodiments of asymmetric edge bladders.

FIG. 15 is a cross-sectional view illustrating another exemplaryembodiment of a substrate receiving member.

FIG. 16 is a cross-sectional view illustrating still another exemplaryembodiment of a substrate receiving member.

FIG. 17 is a cross-sectional view illustrating still another exemplaryembodiment of a substrate receiving member.

FIG. 18 is a cross-sectional view illustrating an exemplary embodimentof a substrate receiving member having at least two perimeter portions.

FIG. 19 is a schematic cross-sectional view of a carrier head in whichthe substrate receiving member of FIG. 18 is mounted.

FIG. 20 is a schematic cross-sectional view of a carrier head accordingto another exemplary embodiment of the present invention.

FIG. 21 is a schematic cross-sectional view of a carrier head accordingto still another exemplary embodiment of the present invention.

FIG. 22 is a schematic cross-sectional view of a carrier head accordingto still another exemplary embodiment of the present invention.

FIGS. 23 and 24 are schematic cross-sectional views explaining theoperation of a carrier head according to a preferred embodiment of thepresent invention.

FIGS. 25, 26 and 27 are cross-sectional views explaining lateralexpansions of a center bladder and an edge bladder according to thedifference of their chamber pressures, and explaining the role of a wallstructure.

FIGS. 28 and 29 are schematic cross-sectional views explaining thestructure and operation of a carrier head further comprising an edgewall structure.

FIG. 30 is a schematic cross-sectional view of a carrier head accordingto still another exemplary embodiment of the present invention.

FIG. 31 is a schematic cross-sectional view of a carrier head accordingto still another exemplary embodiment of the present invention.

FIG. 32 is a schematic cross-sectional view of a carrier head accordingto still another exemplary embodiment of the present invention.

FIG. 33 is a schematic cross-sectional view illustrating a carrier headfurther comprising an intermediate bladder according to anotherexemplary embodiment of the present invention.

FIGS. 34, 35 and 36 are schematic cross-sectional views explaining theoperation of the carrier head of FIG. 33.

FIG. 37 is a schematic cross-sectional view illustrating gaps betweenthe wall structures and the inner surface of substrate receiving memberin a carrier head according to the present invention.

FIG. 38 is a schematic cross-sectional view of a carrier head accordingto still another exemplary embodiment of the present invention.

FIG. 39 is a schematic cross-sectional view of a carrier head accordingto still another exemplary embodiment of the present invention.

FIG. 40 is a schematic cross-sectional view illustrating an exemplaryembodiment of a carrier head without a center bladder.

FIG. 41 is a schematic cross-sectional view illustrating an exemplaryembodiment of a carrier head without an intermediate bladder.

FIG. 42 is a schematic cross-sectional view of a carrier head comprisingan edge bladder according to an embodiment of the present invention.

FIG. 43 is a schematic cross-sectional view of a carrier head furthercomprising an edge wall structure.

FIG. 44 is a schematic cross-sectional view of a carrier head comprisingan edge bladder which is clamped externally.

FIG. 45 is a schematic cross-sectional view of a carrier head includinga connecting member acting also as a wall structure.

FIG. 46 is a schematic cross-sectional view of a carrier head comprisinga center bladder according to another embodiment of the presentinvention.

FIG. 47 is a schematic cross-sectional view of a carrier head includinga connecting member acting also as a wall structure.

DETAILED DESCRIPTION

Hereinafter, preferred embodiments of the present invention will bedescribed with reference to the accompanying drawings. Rather, theseembodiments of the present invention are provided in order to fullyexplain the present invention to those skilled in the art. Therefore, inthe drawings, the shapes of components may be exaggerated for clarity,and the same reference numerals will be used throughout to designate thesame or like components.

FIG. 1 is a schematic cross-sectional view of a carrier head 900according to a preferred embodiment of the present invention. Thecarrier head 900 is configured to, as a basic component, comprise a base100 receiving motive power from a drive shaft 110. A retaining ring 120,which is mounted on a lower part of the base 100, serves to prevent thesubstrate (not shown) from slipping out from the beneath of the carrierhead 900 during CMP. Inside of the retaining ring 120, a substratereceiving member 600 is connected to the lower part of the base 100.

The substrate receiving member 600 comprises a plate portion 602, aperimeter portion 604, and a securing portion 606. The plate portion 602provides two surfaces defined as an outer surface 608 and an innersurface 610 of the substrate receiving member 600, respectively. Thesize and shape of the plate portion 602 conforms to the size and shapeof a substrate to be polished. The outer surface 608 is a substratereceiving surface against which a substrate can be mounted. The innersurface 610, which is opposite to the outer surface 608, is a surface towhich a pressure is applied by a fluid or by a contact through theexpansion of bladders 200, 300. The perimeter portion 604 is awall-shaped part extending away from the plate portion 602 in order toconnect the perimeter portion 602 to the securing portion 606. Thesecuring portion 606 is a part connected to the base 100, which maycomprise a flap or an O-ring. The securing portion 606 seals the innerportion of the substrate receiving member 600 from the outside to form asubstrate receiving member chamber 650. The substrate receiving memberchamber 650 may contain a fluid supplied through a substrate receivingmember fluid passage 612 to maintain a predetermined pressure, which canbe a polishing pressure applied through the plate portion 602 to asubstrate (not shown) during CMP. As a fluid, gas or liquid may be used,and air or nitrogen may be preferably used. The substrate receivingmember 600 may be wholly made of a single material as shown in FIG. 1,and a flexible material may be used for the substrate receiving member600. Rubber may be used as a flexible material, and preferably, rubberhaving good water and chemical resistances, such as silicone rubber andethylene propylene diene monomer (EPDM) rubber, may be used. Thesubstrate receiving member 600 made of a flexible material may befabricated using molding method, by which the plate portion 602 may havea thickness of 0.5 mm to 3.0 mm.

As shown in FIG. 1, inside of the substrate receiving member 600, acenter bladder 200 located over a center area of the inner surface 610of substrate receiving member 600 is connected to the lower part of thebase 100. An edge bladder 300 over an edge area of the inner surface 610of the substrate receiving member 600 is also connected to the lowerpart of the base 100.

The center area of the inner surface 610 may be defined as an areaincluding the center of the inner surface 610, and the size of thecenter area may be represented by a radius R from the center of theinner surface 610 as shown in FIG. 1. In the case in which the innersurface is circular, R may have a value between 20 to 90% of the radiusof inner surface. In the case in which the inner surface isrectangular-shaped, the center area may be defined as an area includingthe center of the inner surface, and the size of the center area may bea reduced size of the inner surface to 20 to 90% in length.

The edge area may be represented by a distance d from the end of theinner surface 610 as shown in FIG. 1. The distance d may have a valuebetween 1 to 20% of a diameter in case of a circular inner surface. Forexample, in the case in which the inner surface 610 has a diameter of300 mm, the edge area may be an area ranging from the end of the innersurface 610 to 3 mm inward or from the end to 60 mm inward. In the caseof a rectangular-shaped inner surface, d may have a value between 1 to20% of the diagonal length of an inner surface. In a certaincircumstance, some positions of an inner surface may belong to a centerarea or to an edge area. In this case, the positions may be consideredto belong to a center area when the bladder on them applies pressurealso to the center of the inner surface, and to belong to an edge areawhen the bladder on them is an edge bladder. In addition, an areabetween center and edge areas may be explained by an intermediate areato be described below.

FIGS. 2 and 3 are perspective views illustrating exemplary embodimentsof the center bladder 200 and edge bladder 300. The center bladder 200includes a disk-shaped bottom portion 202, a wall-shaped side portion204, and a ring-shaped top portion 206 as shown in FIG. 2. For a securesealing, an O-ring part may be formed at the top portion 206. The edgebladder 300 may include a ring-shaped bottom portion 302 and sideportions 304, 304′, and top portions 306, 306′ as shown in FIG. 3. AnO-ring part may be also formed at the top portions 306, 306′ for asecure sealing. The bladders 200, 300 may be made of flexible material.Rubber is suitable for the flexible material, and the rubber includesnatural rubber, silicone rubber, EPDM rubber, chloroprene rubber and thelike. The surface of the bladders 200, 300 may be coated with polymermaterial and the bladders 200, 300 may be protected by attaching aplastic or metal sheet having a thickness of 0.05 mm to 0.3 mm to theinner or outer surface of the bottom portions 202, 302.

Referring to FIG. 1, the center and edge bladders 200, 300 are spacedfrom the inner surface 610 by a distance e, wherein e may have a valuebetween 0 mm to 5 mm when the pressure applied to the bladders 200, 300is same as the pressure applied to the substrate receiving member 600,for example when all the pressures are atmospheric pressure. That is,when the two pressures are the same as each other, the bladders 200, 300don't necessarily have to be spaced away from the inner surface 610 asdepicted in FIG. 1, and rather, may extend further toward the innersurface 610 to contact the inner surface 610, so that e is 0 mm.

At the time of connecting the center and edge bladders 200, 300 to thebase 100, bladder clamps 220, 320 may be used as shown in FIG. 1. Thebladder clamps 220, 320 are inserted first into the bladders 200, 300,respectively, and then clamped to the lower part of the base 100, andthereby the bladders 200, 300 are sealed.

FIGS. 4 and 5 are top views illustrating exemplary embodiments ofbladder clamps 220, 320 for securing the center and edge bladders 200,300, respectively. All of which represent the surfaces that are mountedon the lower part of the base 100 shown in FIG. 1. First, referring toFIG. 4, the center bladder clamp 220 may be disk-shaped, and have screwholes 226 for connecting to the base 100, and a clamp fluid passage 222through which a fluid may pass. In the case in which an O-ring part isin the center bladder 200, a groove 224 may be formed on the top of thecenter bladder camp 220 for a secure sealing. Referring to FIG. 5, theedge bladder clamp 320 may be ring-shaped and have a clamp fluid passage322 through which a fluid may pass. In addition, the bladder clamp 320may have screw holes 326 so that it may be connected to the base 100. Inthe case in which O-ring parts are in the edge bladder 300, grooves 324may be formed on the top of the edge bladder clamp 320 for a securesealing. Iron alloys, aluminum alloys, or plastics may be used for thematerial of the bladder clamps 220, 320. The bladders 200, 300 may beexpanded by the pressure of a fluid supplied through bladder fluidpassages 212, 312 in FIG. 1 and the clamp fluid passages 222, 322. As afluid, gas or liquid may be used, and air or nitrogen may be preferablyused.

FIGS. 6 and 7 are perspective views illustrating exemplary embodimentsof wall structures 700, 710. Referring to FIG. 6, the wall structure 700may have a cylindrical shape in which the center is empty. The wallstructure 700 may include a flange 702 at the top which is to beconnected to the base 100. At the top, screw holes 704 may be formed forconnecting to the base 100. In addition, a wall structure fluid passage706 may be formed from the top surface to the bottom surface of the wallstructure 700. Although not shown, the flange 702 may have grooves forO-rings to seal securely at the time of connecting the wall structure700 to the base 100. The wall structure fluid passage 706 may beconnected to the substrate receiving member fluid passage 612 for fluidsupplying to the substrate receiving member chamber 650. Referring toFIG. 7, the wall structure 710 has screw holes 714 at the top forconnecting to the base 100. Grooves 718 may be formed on surfaces of theinner and outer sides 716, such that a fluid supplied through thesubstrate receiving member fluid passage 612 may be easily released intothe substrate receiving member chamber 650. The wall structures 700, 710serve to limit the expansion of the bladders 200, 300, therefore, theymay be preferably made of material capable of maintaining rigidity so asnot to be easily bent, such as aluminum alloys or iron alloys.

FIG. 8 is a schematic cross-sectional view of a carrier head includingan edge bladder 370 according to another exemplary embodiment, whereinthe edge bladder 370 is clamped externally such that no clamp is neededin the internal portion thereof. Meanwhile, as shown in FIG. 8, the edgebladder 370 is clamped by an outside clamp 380 and an inside clamp 770.Here, the inside clamp 770 may have a lower portion extended toward theinner surface 610 so that it may serve as a wall structuresimultaneously, where it can be noted that a clamp and a wall structuremay be integrally formed in one body. The inside clamp 770 may have afluid passage (not shown) so that a fluid may pass therethrough. Theedge bladder 370 forms a bladder chamber 340 isolated from the substratereceiving member chamber 650, and expands by a fluid supplied throughthe bladder fluid passage 312 and contracts by a vacuum. The bottomportion of the edge bladder 370 in FIG. 8 is depicted to be spaced awayfrom the inner surface 610. However, when the pressure applied to theedge bladder 370 is same as the pressure applied to the substratereceiving member 600, the edge bladder 370 does not necessarily have tobe spaced away from the inner surface 610, and may rather have a shapeextending toward the inner surface 610 so as to contact the innersurface 610.

FIG. 9 is a perspective view illustrating an exemplary embodiment of theedge bladder 370 described above, wherein the annular space between aninside portion 374 and an outside portion 376 forms the bladder chamber340 when the edge bladder 370 is connected to the base 100.

FIG. 10 is a cross-sectional view along line AA′ of FIG. 9, wherein theedge bladder 370 includes also an inside securing portion 372, anoutside securing portion 373, and a bottom portion 378. The inside andoutside securing portions 372, 373 extend outwardly from the inside andoutside portions 374, 376 in order to enable the edge bladder 370 to beclamped externally. A round surface, indicated as R, may be formedbetween the side portions 374, 376 and the bottom portion 378. The edgebladder 370 may have an internal width W of 2 mm to 30 mm and aninternal depth H of 10 mm to 40 mm.

FIGS. 11 to 14 are cross-sectional views illustrating still otherexemplary is embodiments of edge bladders. Referring to FIG. 11, an edgebladder 380 may have a bottom portion 382 with an entirely roundsurface. Referring to FIG. 12, an edge bladder 384 may include an insideportion 374′ and an outside portion 376′ having pleats 386. When thepleats 386 are smoothed out, the internal depth H may be increased moreeasily than without the pleats 386. In addition, in the case in whichthe edge bladder 384 contracts due to a pressure difference, the pleats386 may help a bottom portion 388 move upwardly. Referring to FIG. 13,an edge bladder 390 may have a structure in which an inside portion 392and an outside portion 394 are asymmetric with respect to a center lineCC′ so that the inside portion 392 and the outside portion 394 may beelongated in different degrees. For example, the outside portion 394 maybe formed longer than the inside portion 392 so that the outside portion394 may be elongated longer than the inside portion 392. Referring toFIG. 14, in an edge bladder 396, the number of pleats of an insideportion 398 may be different from that of an outside portion 399 so thatthey may be elongated in different degrees.

FIG. 15 is a cross-sectional view illustrating another exemplaryembodiment of a substrate receiving member 620, wherein a plate portion626 comprises a first plate 622 made of a flexible material like theperimeter portion 604 and a second plate 624 made of a material havinghigher stiffness than that of the first plate 622. It is preferable thatthe size of the second plate 624 is similar to the size of the firstplate 622, and it is more preferable that the diameter or side lengthdifference between them is less than 1%. The first plate 622 may be madeof a rubber having good chemical resistance, such as silicone rubber orEPDM rubber, and the second plate 624 may be made of plastic such aspolycarbonate or polyethylene terephthalate (PET). The first plate 622may have a thickness of 0.5 mm to 2.5 mm, and the second plate 624 mayhave a thickness of 0.2 mm to 1.0 mm. The second plate 624 may beattached to the upper surface of the first plate 622 using adhesive, orthe perimeter portion 604 may have a groove (not shown) to insert thesecond plate 624 thereby making it possible to couple the second plate624 to the first plate 622. When the second plate 624 is attached to theupper surface of the first plate 622, then an upper surface 628 of thesecond plate 624 becomes an inner surface of the substrate receivingmember 620 to which bladders may contact. Although the above mentionedexemplary embodiment has described the case in which the plate portion626 is formed with the two plates 622, 624, a plate portion may beformed with more than two plates.

FIG. 16 is a cross-sectional view illustrating still another exemplaryembodiment of a substrate receiving member 630, wherein a plate portion634 is made of a material having higher strength than that of theperimeter portion 604 and the securing portion 606. By increasing thestrength of the plate portion 634, a substrate (not shown) may notrespond too sensitively to a local polishing pressure. The plate portion634 may be made of a plastic, such as polycarbonate or PET, and have athickness of 0.5 mm to 2.5 mm. Referring to FIG. 17, a substratereceiving member 630′ may include a felt type mounting film 636 (forexample, R301 mounting film from Nitta Haas) attached to the lowersurface of the plate portion 634.

FIG. 18 is a cross-sectional view illustrating an exemplary embodimentof a substrate receiving member 640 having at least two perimeterportions. The substrate receiving member 640 may comprise a plateportion 642 providing an outer surface 641 for receiving a substrate,and a vertical perimeter portion 644 extending from the plate portion642 wherein the vertical perimeter portion forms an angle of 84° to 96°with respect to the plate portion 642, and an inclined perimeter portion645 extending from the vertical perimeter portion 644 wherein theinclined perimeter portion extends outwardly forming an angle of 6° to40° (θ in FIG. 18) with respect to the vertical perimeter portion 644. Asecuring portion 646 is also included for connecting the substratereceiving member 640. Although not shown, the angle at the intersectionof the inclined perimeter portion 645 with the vertical perimeterportion 644 may be formed smoothly so that it may have a round surface.A radius of curvature forming the round surface may have a value of 0.5mm to 5 mm. The substrate receiving member 640 may be made of flexiblematerials, but the vertical perimeter portion 644 may be stiffer thanthe inclined perimeter portion 645. For example, the hardness of thevertical perimeter portion 644 may be 60 to 90 Shore-A in Durometervalue, and the hardness of the inclined perimeter portion 645 may be 30to 60 Shore-A. The securing portion 646 may include an O-ring structurefor secure sealing. Although the above mentioned exemplary embodimenthas described only two perimeter portions, more perimeter portions canbe included to the above vertical-inclined perimeter structure.

FIG. 19 is a schematic cross-sectional view illustrating a carrier head904 in which the above mentioned substrate receiving member 640 ismounted. The carrier head 904 includes a retaining ring 124 that has aninclined upper portion in order to easily receive the inclined perimeterportion 645 of the substrate receiving member 640.

As described above, in the exemplary embodiments of the presentinvention, the substrate receiving members 600, 620, 630, 640, which areeach made in a various way, may be used. However, for simplicity, thecase in which the substrate receiving member is wholly made of a sameflexible material as shown in FIG. 1 will be described.

FIG. 20 is a schematic cross-sectional view illustrating a carrier head906 according to another exemplary embodiment of the present invention.Without direct connection to a base 150, the bladder clamps 220, 320 andthe wall structure 700 may be clamped first to a connecting member 152,and then the connecting member 152 is fastened to the base 150 by screws(not shown), or the like, thereby making it possible to connect thecenter and edge bladders 200, 300 and the wall structure 700 to thelower part of the base 150. The connecting member 152 may have fluidpassing holes 153 to connect the bladder fluid passages 212, 312 to theclamp fluid passages 222, 322, and the substrate receiving member fluidpassage 612 to a fluid passage (not shown) formed in the wall structure700.

FIG. 21 is a schematic cross-sectional view illustrating a carrier head908 according to still another exemplary embodiment of the presentinvention. The bladder clamps 220, 320 are clamped first to a connectingmember 162 in which a wall structure 700′ is integrally formed in onebody. The connecting member 162 is fastened to a base 160 by screws (notshown) or the like to connect the center and edge bladders 200, 300 tothe lower part of the base 160. The connecting member 162 may have fluidpassing holes 163 to connect the bladder fluid passages 212, 312 to theclamp fluid passages 222, 322, and the substrate receiving member fluidpassage 612 to a fluid passage (not shown) formed in the wall structure700′.

FIG. 22 is a schematic cross-sectional view illustrating a carrier head910 according to still another exemplary embodiment of the presentinvention. Fluid needed in the substrate receiving member chamber 650may be supplied through the substrate receiving member fluid passage 612and then holes 614 formed in the lower part of the base 100. Here, whenthe bladders 200, 300 expand, the holes 614 may be blocked. Therefore,the outer surface of the bladders 200, 300 may have groove-shapedtextures (not shown) so that the fluid may flow even after the bladders200, 300 block the holes 614.

FIGS. 23 and 24 are schematic cross-sectional views explaining theoperation of the carrier head 900 described above. Referring to FIG. 23,pressures applied to the substrate receiving member fluid passage 612,the center bladder fluid passage 212, and the edge bladder fluid passage312 are designated as P1, P2, and P3, respectively. The pressures P1, P2and P3 may be controlled independently, and the fluid passages 612, 212,312 may be applied with not only positive pressures relative to anatmospheric pressure, but also a negative pressure, that is, a vacuum.In addition, when each fluid passage is open to the atmosphere, P1, P2,and P3 may be in a vent state which is same as an atmospheric pressure.In FIG. 23, a positive pressure P1 is applied to the substrate receivingmember fluid passage 612, and a vacuum or an atmospheric pressure (ventstate) is applied to the center and edge bladder fluid passages 212,213. Therefore, the substrate receiving member chamber 650 may maintainthe pressure of P1, and the pressure of P1 may be applied to a substrate50 through the plate portion 602 of the substrate receiving member 600.Referring to FIG. 24, positive pressures P2 and P3 are applied to thecenter bladder fluid passage 212 and the edge bladder fluid passage 312,respectively, and an atmospheric pressure is applied to the substratereceiving member fluid passage 612. The center bladder 200 to which thepositive pressure P2 is applied expands and stops expanding downward atthe moment of contacting the inner surface 610 and also stops expandinglaterally at the moment of contacting the wall structure 700. The innersurface 610 contacted by the center bladder 200 may be a center area ofthe inner surface 610 defined by the wall structure 700. Here, theapplied pressure to the inner surface 610 may be the pressure P2 in thecenter bladder chamber 250. More precisely, the applied pressure is tobe obtained by subtracting or adding the stress needed in expanding orcontracting the center bladder 200. However, since the subtracted oradded stress is much smaller than that in the center bladder chamber250, the pressure applied to the inner surface 610 is consideredidentical to the pressure in the center bladder chamber 250 forconvenience. Again, the pressure P2 is applied through the plate portion602 to a center area of the substrate 50. Likewise, the inner surface610 of the substrate receiving member 600 contacted by the edge bladder300 may be an edge area of the inner surface 610 defined by the wallstructure 700. Here, the applied pressure to the edge area of the innersurface 610 may be the pressure P3 in the edge bladder chamber 350. Thepressure P3 is applied through the plate portion 602 to an edge area ofthe substrate 50. Therefore, by adjusting P2 and P3 which areindependently controllable, higher polishing pressure may be applied tothe center area or to the edge area of the substrate 50, thereby makingit possible to maintain good polishing rate uniformity.

Therefore, referring to FIG. 24, the carrier head 900 according to apreferred embodiment of the present invention comprises: the base 100;the substrate receiving member 600 connected to the lower part of thebase 100, having the outer surface 608 against which the substrate 50can be mounted; the two bladders 200, 300 positioned inside of thesubstrate receiving member 600 and connected to the lower part of thebase 100, wherein the two bladders 200, 300 can apply pressureindependently to the predetermined areas of the inner surface 610 of thesubstrate receiving member 600 by expanding and contacting the innersurface 610; and the wall structure 700 connected to the lower part ofthe base 100, wherein the wall structure 700 can limit lateralexpansions of the two bladders 200, 300.

FIGS. 25 to 27 are cross-sectional views explaining lateral expansionsof the center and edge bladders 200, 300 according to the difference oftheir chamber pressures, and explaining how the wall structure 700serves. First, referring to FIG. 25 without the wall structure, when thepressure P2 in the center bladder chamber 250 is same as the pressure P3in the edge bladder chamber 350, there exists no overlap betweenbladders 200, 300 in the area M in which two bladders 200, 300 and thesubstrate receiving member 600 meet each other because a balance offorce is maintained. Therefore, the pressure may be uniformly applied tothe substrate receiving member 600. However, as shown in FIG. 26, in thecase in which the pressure P2 in the center bladder chamber 250 ishigher than the pressure P3, the center bladder 200 pushes the edgebladder 300 and the edge bladder 300 is folded in the area N in whichthe two bladders 200, 300 and the substrate receiving member 600 meeteach other. The pressure applied to the substrate receiving member 600may be affected by the degree to which the edge bladder 300 is foldedand the position in which it is folded, and as a result, the pressuremay be applied irregularly to the substrate receiving member 600 in thearea N.

Meanwhile, FIG. 27 shows an example in which lateral expansions arestopped by the wall structure 700. The center bladder 200 may notcontinuously expand as that of FIG. 26, and the expansion may be limitedby the wall structure 700, and the pressure P2 is applied only to anarea A2 of the inner surface 610 of the substrate receiving member 600.In addition, the edge bladder 300 to which the pressure P3 (which issmaller than P2) is applied may not be pushed back by the center bladder200 and may rather expand up to an area where the wall structure 700limits, such that the pressure P3 may be applied to an A3 area of theinner surface 610. The wall structure 700 is connected to the base 100and spaced away from the inner surface 610 by h. The gap h may rangefrom 1 mm to 10 mm during CMP. The center bladder 200 may contact theedge bladder 300 only through the gap h. The degree of expansion throughthe gap is proportional to the size of gap. By controlling the size ofgap h, the center bladder 200 may be allowed to contact the edge bladder300 partially, or may be prevented completely from contacting the edgebladder 300. When the two bladders 200, 300 are expanded, a positivepressure lower than P2 and P3 may be applied in a space between the twobladders 200, 300 through a wall structure fluid passage (not shown)connected to the substrate receiving member fluid passage 612.

FIGS. 28 and 29 are schematic cross-sectional views explaining thestructure and operation of a carrier head 920 further comprising an edgewall structure 730. Referring to FIG. 28, the carrier head 920 includesthe edge wall structure 730 connected to the lower part of the base 100and located between the edge bladder 300 and the perimeter portion 604of the substrate receiving member 600. The edge wall structure 730 maylimit a lateral expansion of the edge bladder 300 toward outer directionand thus may limit a contact between the perimeter portion 604 and theedge bladder 300. The edge wall structure 730 also can have a hollowcylindrical shape. Referring to FIG. 29, when the edge bladder 300 isexpanding, the edge wall structure 730 limits the contact with theperimeter portion 604. Depending on the size of a gap between the edgewall structure 730 and the inner surface 610, denoted w in FIG. 29, theedge bladder 300 may be allowed to contact the perimeter portion 604partially, or may be prevented completely from contacting the perimeterportion 604. The substrate receiving member fluid passage 612 can beconnected to the edge wall structure 730 so that a fluid can be suppliedthrough a wall structure fluid passage (not shown) or grooves (notshown) formed in the edge wall structure 730.

FIGS. 30 to 32 are schematic cross-sectional views of carrier heads 922,924, 926 according to still other exemplary embodiments of the presentinvention. Referring to FIG. 30, a fluid supplied to the substratereceiving member chamber 650 through the edge wall structure 730 may beseparately controlled through a wall structure fluid passage 614.Referring to FIG. 31, without direct connection to the base 150, thebladder clamps 220, 320 and the wall structures 700, 730 may be clampedfirst to a connecting member 154 and then the connecting member 154 isfastened to the base 150 by screws (not shown), or the like, therebymaking it possible to connect the center and edge bladders 200, 300 andthe wall structures 700, 730 to the lower part of the base 150. Theconnecting member 154 may have fluid passing holes 155 to connect thebladder fluid passages 212, 312 to the clamp fluid passages 222, 322,and the substrate receiving member fluid passage 612 to fluid passages(not shown) formed in the wall structures 700, 730. Referring to FIG.32, the bladder clamps 220, 320 are clamped first to a connecting member164 in which wall structures 700′, 730′ are integrally formed in onebody. The connecting member, or integrated wall structure, 164 isfastened to the base 160 by screws (not shown) or the like to connectthe center and edge bladders 200, 300 to the lower part of the base 160.The connecting member 164 may have fluid passing holes 165 to connectthe bladder fluid passages 212, 312 to the clamp fluid passages 222,322, and the substrate receiving member fluid passage 612 to fluidpassages (not shown) formed in the wall structure 700′, 730′.

FIGS. 33 to 36 are schematic cross-sectional views illustrating acarrier head 940 according to another exemplary embodiment of thepresent invention, and explaining the operation thereof. Referring toFIG. 33, the carrier head 940 further includes an intermediate bladder400 to control independently a pressure in an intermediate area. Theintermediate area may be defined as an area between edge and centerbladders 300, 500 regardless of the number of bladders. In the case inwhich there is no center bladder, which means there is no bladderpressuring the center of the inner surface 610, the area between theedge bladder and the area without the center bladder may be defined asintermediate area. The center bladder 500 and the edge bladder 300 mayexpand by a fluid supplied through a center bladder fluid passage 512and an edge bladder fluid passage 312, respectively. During expansion,the center bladder 500 is limited laterally by a center wall structure760, by which the center bladder 500 contacts only a center area of theinner surface 610 in the entire inner surface 610 of the substratereceiving member 600. The lateral expansion of the edge bladder 300 islimited by an intermediate wall structure 750 and an edge wall structure740, by which the edge bladder 300 contacts only an edge area in theentire inner surface 610. Similarly, the lateral expansion of theintermediate bladder 400 is limited by the intermediate wall structure750 and the center wall structure 760, by which the intermediate bladder400 contacts only an intermediate area in the entire inner surface 610.The intermediate bladder 400 may have a ring shape as the edge bladder300. A fluid pressure, vacuum or atmospheric pressure can be applied tothe intermediate bladder 400 through an intermediate bladder fluidpassage 412. Also the intermediate bladder 400 may be connected to thelower part of the base 100 by inserting an intermediate bladder clamp420 into the intermediate bladder 400 and then clamping the intermediatebladder clamp 420 to the base 100. A clamp fluid passage 422 is formedin the intermediate bladder clamp 420 to connect to the intermediatebladder fluid passage 412.

Referring to FIG. 34, when a pressure P3 is applied to the edge bladderfluid passage 312, the edge bladder 300 expands and contacts the innersurface 610 of the substrate receiving member 600 while forming an edgebladder chamber 350 with the pressure P3. The inner surface 610contacted by the edge bladder 300 may be an edge area of the innersurface 610 defined by the edge wall structure 740 and the intermediatewall structure 750. The applied pressure to the inner surface 610 may bethe pressure P3 in the edge bladder chamber 350. Again, this pressure isapplied to an edge area of a substrate 50 through the plate portion 602of substrate receiving member 600. Similarly, the intermediate bladder400 where a pressure P4 is applied forms an intermediate bladder chamber450 with the pressure P4 and contacts an intermediate area of the innersurface 610 thereby the pressure P4 is transferred to an intermediatearea of the substrate 50. Likewise, the center bladder 500 where apressure P5 is applied forms a center bladder chamber 550 with thepressure P5 and contacts a center area of the inner surface 610 therebythe pressure P5 is transferred to a center area of the substrate 50.Here, an atmospheric pressure or a positive pressure smaller than P3, P4and P5 can be applied to the substrate receiving member fluid passage612. Therefore, by adjusting pressure P3, P4 and P5 independently,polishing rates on the center, intermediate and edge areas of thesubstrate 50 can be controlled.

Referring to FIG. 35, the edge bladder 300 with a pressure P3 expandsand contacts an edge area of the inner surface 610, but the intermediatebladder 400 where a pressure P4 is applied and the center bladder 500where a pressure P5 is applied contract. The center and intermediateareas of the substrate 50 receive pressure directly from the substratereceiving member chamber 650 where a pressure P1 is applied. In thiscase, P1 has a higher value than P4 and P5 but a smaller value than P3.Such a combination is feasible when a same pressure is necessary for thecenter and intermediate areas and a higher pressure is necessary for theedge area. Also in the case in which the center bladder 500 and theintermediate bladder 400 expand and contact the inner surface 610 likein FIG. 34, a similar pressure distribution can be obtained by adjustingP1, P3, P4 and P5.

Referring to FIG. 36, the center bladder 500 with a pressure P5 expandsand contacts a center area of the inner surface 610 but the intermediatebladder 400 where a pressure P4 is applied and the edge bladder 300where a pressure P3 is applied contract. The intermediate and edge areasof the substrate 50 receive pressure directly from the substratereceiving member chamber 650 where pressure P1 is applied. In this case,P1 has a higher value than P3 and P4 but a smaller value than P5. Such acombination is feasible when a same pressure is necessary for theintermediate and edge areas and a higher pressure is necessary for thecenter area.

Therefore, referring to FIG. 34, the carrier head 940 according toanother exemplary embodiment of the present invention comprises: thebase 100; the substrate receiving member 600 connected to the lower partof the base 100, having the outer surface 608 against which thesubstrate 50 can be mounted; the three bladders 300, 400, 500 positionedinside of the substrate receiving member 600 and connected to the lowerpart of the base 100, wherein the three bladders 300, 400, 500 can applypressure independently to the predetermined areas of the inner surface610 of the substrate receiving member 600 by expanding and contactingthe inner surface 610; and the three wall structures 740, 750, 760connected to the lower part of the base 100, wherein the three wallstructures 740, 750, 760 can limit lateral expansions of the threebladders 300, 400, 500.

Above examples showed how the three bladders 300, 400, 500 can controlthe polishing rate in the edge, intermediate and center areas of asubstrate. However, the number of bladders is not limited to 3. Insteadthe number can be increased as long as the space of the base 100permits. For example, a carrier head for 450 mm silicon wafers can haveup to 12 bladders while a carrier head for 300 mm silicon wafers canhave up to 8 bladders.

FIG. 37 is schematic a cross-sectional view illustrating gaps betweenthe wall structures 740, 750, 760 and the inner surface 610 for thecarrier head 940 shown above. Here, the gaps h1, h2, and h3 may beadjusted so that the de-chucking of a substrate from a polishing pad canbe securely performed. It is advantageous that the gap becomes larger asit goes toward the center area of the substrate receiving member 600,say h1<h2<h3. This is to let the plate portion 602 have a form ofsuction cup when the vacuum is applied to the inside of the substratereceiving member 600 to de-chuck a substrate.

FIGS. 38 and 39 are schematic cross-sectional views illustrating carrierheads 942, 944 according to still other exemplary embodiments of thepresent invention. Referring to FIG. 38, bladder clamps 320, 420, 520are clamped first to a connecting member 172 in which wall structures740′, 750′, 760′ are integrally formed in one body. The connectingmember, or integrated wall structure, 172 is fastened to a base 170 byscrews (not shown) or the like to connect the bladders 300, 400, 500 tothe lower part of the base 170. The connecting member 172 may have fluidpassing holes 173 to connect the bladder fluid passages 312, 412, 512 toclamp fluid passages 322, 422, 522 respectively, and the substratereceiving member fluid passage 612 to fluid passages (not shown) formedin the wall structure 740′, 750′, 760′. FIG. 39 represents an example ofplural connecting members 174, 176 which are each integrally formed withwall structures 740″, 750″, 760″. After the edge bladder 300 is clampedto a first connecting member 174, where an edge wall structure 740″ andan intermediate wall structure 750″ are integrally formed, the firstconnecting member 174 is fastened to a second connecting member 176where a center wall structure 760″ is integrally formed. After theintermediate and center bladders 400, 500 are clamped to the secondconnecting member 176, the second connecting member is fastened to thebase 170 by screws (not shown) or the like to connect the bladders 300,400, 500 and the wall structures 740″, 750″, 760″ to the lower part ofthe base 170. The first and second connecting members 174, 176 may havefluid passing holes 175, 177 to connect the bladder fluid passages 312,412, 512 to the clamp fluid passages 322, 422, 522 respectively, and thesubstrate receiving member fluid passage 612 to fluid passages (notshown) formed in the wall structure 740″, 750″, 760″.

FIGS. 40 and 41 are schematic cross-sectional views illustrating carrierheads 946, 948 where a bladder is removed. First, FIG. 40 shows thecarrier head 946 in which the above mentioned center bladder 500 andmembers needed to operate the center bladder are removed. Here, apressure in the substrate receiving member chamber 650 is applied to acenter area of the inner surface 610. At this time, if a pressure isabout to be applied to an intermediate area of the inner surface 610 byan expansion of the intermediate bladder 400, the pressure in thesubstrate receiving member chamber 650 is required to be smaller thanthe pressure applied to the intermediate bladder 400. FIG. 41 shows thecarrier head 948 in which the above mentioned intermediate bladder 400and members needed to operate the intermediate bladder are removed.Here, a pressure in the substrate receiving member chamber 650 isapplied to an intermediate area of the inner surface 610. At this time,if the center and edge bladders 500, 300 are about to expand and applypressures to the inner surface 610, the pressure in the substratereceiving member chamber 650 is required to be smaller than thepressures applied to the center and edge bladders 500, 300.

As described above, the carrier heads according to the exemplaryembodiments of the present invention include a plurality of bladders,but pressures from bladders does not have to be applied to entire areasof the inner surface of the substrate receiving member during CMP.Therefore, the bladder of the corresponding area may be contracted orremoved.

FIGS. 42 to 47 are schematic cross-sectional views illustrating carrierheads 960, 962, 964, 966, 970, 972 including a single bladder. Here,terms for all members and materials of all members are the same as thoseof carrier heads including a plurality of bladders described above. Samecomponents will be described as the same reference numerals, and anoverlapped description will be omitted.

First, referring to FIG. 42, the carrier head 960 according to anembodiment of the present invention comprises: a base 100; a substratereceiving member 600 connected to a lower part of the base 100, havingan outer surface 608 against which a substrate can be mounted; an edgebladder 300 positioned inside of the substrate receiving member 600 andconnected to the lower part of the base 100, wherein the edge bladder300 can apply pressure to an edge area of an inner surface 610 of thesubstrate receiving member 600 by expanding and contacting the innersurface 610; and a wall structure 70 connected to the lower part of thebase 100, wherein the wall structure can limit an inward expansion ofthe edge bladder 300.

The wall structure 70 of the present embodiment may have a same form asthat of the wall structure 700 described above. However, the wallstructure 70 may not have a fluid passage through which a fluid may passas in the above described wall structure 700.

Referring to FIG. 43, the carrier head 962 further comprises an edgewall structure 72 connected to the lower part of the base 100 andlocated between the edge bladder 300 and the perimeter portion 604 ofthe substrate receiving member 600. The edge wall structure 72 may limita lateral expansion of the edge bladder 300 toward outer direction andthus may limit a contact between the perimeter portion 604 and the edgebladder 300.

Referring to FIG. 44, the carrier head 964 comprises an edge bladder 370clamped externally such that no clamp is needed in the internal portionthereof. Meanwhile, the edge bladder 370 is clamped by an outside clamp76 and an inside clamp 74. Here, the inside clamp 74 may have a lowerportion extended toward the inner surface 610 so that it may serve as awall structure simultaneously. The edge bladder 370 forms a bladderchamber 340 isolated from the substrate receiving member chamber 650,and expands by a fluid supplied through the bladder fluid passage 312and contracts by a vacuum. The bottom portion of the edge bladder 370 inFIG. 44 is spaced away from the inner surface 610. However, when thepressure applied to the edge bladder 370 is same as that applied to thesubstrate receiving member 600, the edge bladder 370 does notnecessarily have to be spaced away from the inner surface 610, and mayhave a shape extending toward the inner surface 610 so as to contact theinner surface 610.

Referring to FIG. 45, the carrier head 966 includes a connecting member180. Without direct connection to the base 100, the bladder clamp 320may be clamped first to the connecting member 180 and then theconnecting member 180 is fastened to the base 100 by screws (not shown),or the like, thereby making it possible to connect the edge bladder 300to the lower part of the base 100. Here, as shown, a center portion ofthe connecting member 180 may extend toward the inner surface 610 toserve as a wall structure to limit an inward expansion of the edgebladder 300. The connecting member 180 may have fluid passing holes 182to connect the substrate receiving member fluid passage 612 to thesubstrate receiving member chamber 650, and to connect the bladder fluidpassage 312 to the clamp fluid passage 322.

Referring to FIG. 46, the carrier head 970 according to anotherembodiment of the present invention comprises: a base 100; a substratereceiving member 600 connected to a lower part of the base 100, havingan outer surface 608 against which a substrate can be mounted; a centerbladder 200 positioned inside of the substrate receiving member 600 andconnected to the lower part of the base 100, wherein the center bladder200 can apply pressure to a center area of an inner surface 610 of thesubstrate receiving member 600 by expanding and contacting the innersurface 610; and a wall structure 70 connected to the lower part of thebase 100, wherein the wall structure can limit an outward expansion ofthe center bladder 200.

Referring to FIG. 47, the carrier head 972 includes a connecting member184. Without direct connection to the base 100, the bladder clamp 220may be clamped first to the connecting member 184 and then theconnecting member 184 is fastened to the base 100 by screws (not shown),or the like, thereby making it possible to connect the center bladder200 to the lower part of the base 100. Here, as shown, an edge portionof the connecting member 184 may extend toward the inner surface 610 toserve as a wall structure to limit an outward expansion of the centerbladder 200. The connecting member 184 may have fluid passing holes 186to connect the substrate receiving member fluid passage 612 to thesubstrate receiving member chamber 650, and to connect the bladder fluidpassage 212 to the clamp fluid passage 222.

As set forth above, the carrier head for a chemical mechanical polishingsystem may independently control polishing pressure applied to eachpredetermined area of the substrate during CMP, thereby making itpossible to control easily the uniformity of polishing rate.

Although the embodiments of the present invention have been disclosedfor illustrative purposes, it will be appreciated that the presentinvention is not limited thereto, and those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the invention.

Accordingly, any and all modifications, variations or equivalentarrangements should be considered to be within the scope of theinvention, and the detailed scope of the invention will be disclosed bythe accompanying claims.

What is claimed is:
 1. A carrier head for a chemical mechanicalpolishing system, comprising: a base; a substrate receiving memberconnected to a lower part of the base, having an outer surface againstwhich a substrate can be mounted; at least two bladders positionedinside of the substrate receiving member and connected to the lower partof the base, wherein the at least two bladders can apply pressureindependently to predetermined areas of an inner surface of thesubstrate receiving member by expanding and contacting the innersurface; and at least one wall structure connected to the lower part ofthe base, wherein the at least one wall structure can limit lateralexpansions of the at least two bladders.
 2. The carrier head of claim 1,wherein the substrate receiving member comprises a plate portion, aperimeter portion, and a securing portion.
 3. The carrier head of claim2, wherein the plate portion comprises a first plate and a second plateattached to an upper surface of the first plate.
 4. The carrier head ofclaim 3, wherein the second plate is formed of a material having ahigher stiffness than that of the first plate.
 5. The carrier head ofclaim 1, wherein the predetermined areas can be partitioned into acenter area and an edge area of the inner surface, and an intermediatearea between the center area and the edge area.
 6. The carrier head ofclaim 1, wherein the numbers of the at least two bladders are from 2 to12.
 7. The carrier head of claim 1, wherein the at least two bladdersare formed of a flexible material.
 8. The carrier head of claim 7,wherein the flexible material is a rubber.
 9. The carrier head of claim1, wherein the at least two bladders are respectively connected to thelower part of the base by at least one bladder clamp.
 10. The carrierhead of claim 9, wherein the at least one bladder clamp and the at leastone wall structure are integrally formed in one body.
 11. The carrierhead of claim 1, wherein the at least two bladders are connected to thelower part of the base by fastening a connecting member to the baseafter the at least two bladders are clamped to the connecting member.12. The carrier head of claim 1, further comprising a wall structurethat can limit a contact between a perimeter portion of the substratereceiving member and a bladder located over an edge area of the innersurface among the at least two bladders.
 13. The carrier head of claim1, wherein securing portions of a bladder located over an edge area ofthe inner surface among the at least two bladders extend outwardly. 14.The carrier head of claim 1, wherein the at least one wall structure isconnected to the lower part of the base by fastening a connecting memberto the base after the at least one wall structure is clamped to theconnecting member.
 15. The carrier head according to claim 14, whereinthe at least one wall structure and the connecting member are integrallyformed in one body.
 16. The carrier head of claim 1, wherein the atleast one wall structure can further limit a contact between twoadjacent bladders among the at least two bladders.
 17. A carrier headfor a chemical mechanical polishing system, comprising: a base; asubstrate receiving member connected to a lower part of the base, havingan outer surface against which a substrate can be mounted; a bladderpositioned inside of the substrate receiving member and connected to thelower part of the base, wherein the bladder can apply pressure to apredetermined area of an inner surface of the substrate receiving memberby expanding and contacting the inner surface; and at least one wallstructure connected to the lower part of the base, wherein the at leastone wall structure can limit a lateral expansion of the bladder.
 18. Asubstrate receiving member used in a carrier head for a chemicalmechanical polishing system, comprising: a plate portion providing anouter surface for receiving a substrate; a vertical perimeter portionextending from the plate portion, wherein the vertical perimeter portionforms an angle of 84° to 96° with respect to the plate portion; and aninclined perimeter portion extending from the vertical perimeterportion, wherein the inclined perimeter portion extends outwardlyforming an angle of 6° to 40° with respect to the vertical perimeterportion.
 19. The substrate receiving member of claim 18, wherein thevertical perimeter portion is stiffer than the inclined perimeterportion.